A unitized core grip is disclosed in U.S. Pat. No. 3,996,417 to Annas as having a common extrusion design incorporating three equally disposed outer lobes retained by a circular or right circular cylindrical web member. The web member provides a circular cylindrical bore to receive the exposed, projecting end of a reinforcing core of an electrical conductor, typically an aluminum conductor steel reinforced (ACSR).
ACSR is a concentrically stranded conductor composed of at least one layer of hard-drawn aluminum wire stranded with a high strength coated steel core. The core may include a single wire or multiple strands depending on the size. Corrosion protection is available through the application of grease to the core or infusion of the complete cable with grease.
The existing conventional design provides a comparatively restrictive right circular cylindrical bore, lined with an abrasive grit. The grit enhances the purchase between the core grip and the steel strands typical of ACSR type conductors. The strands of the inner core of ACSR conductors are of very high tensile strength. They have a propensity to unwind and splay outwardly when the conductive aluminum strands are removed to expose the inner core strands. Due to the comparatively close relationship between the inner diameter of the core grip and the outer diameter of the conductor core, substantial difficulty is encountered while attempting to introduce the core strands into a conventional cylindrical bore.
Insertion of the core strands into the bore of the Annas patent device, due to the minimal space provided, results in the ends of the steel strands abutting the abrasive grit, thus scraping them away and pushing them out the opposite end. During the compression operation, insufficient grit is retained within the bore to provide sufficient keying of the internal surface of the core grip with the steel core stranding.
Accordingly, a need exists for a unitized core grip configured with a tri-lobe design including a configuration providing minimal resistance towards buckling. There also exists a need for a unitized core grip that, when compressed, the inner face of the three lobes results in an inner space, without the splaying of strands. Further, a need exists for knee sections of web members having an initial propensity to deflect outwardly, provide much less resistance, and thus more compressive force to move the lobes radially inward into intimate and secure gripping contact against the core of the cable.